The present invention relates to an isolator design that provides a simple method to incorporate an isolator to a fabricated fuel rail design. Specifically, the invention is a snap-on rail mounting isolator that reduces heat transfer from a metallic intake manifold to a metal-fabricated fuel rail.
Fuel rails for supplying gasoline fuel to an internal combustion engine are well known in the art. These fuel rails generally provide a conduit from which fuel is distributed to a plurality of individual fuel injectors (i.e. xe2x80x9cmulti-pointxe2x80x9d fuel injection).
In the most common arrangement, fuel is pumped from a fuel reservoir, through a fuel supply line, to the fuel rail. Fuel flows through the fuel rail to a plurality of fuel injectors. The fuel rail is attached to the top of the fuel injectors, and supplies fuel into the upper end of each fuel injector, which then injects the fuel into the intake manifold of the engine. Normally, not all of the fuel passing through the rail is fed to the injectors. The remaining fuel passes through the fuel rail to a fuel return line. Typically, a fuel pressure regulator is employed in the fuel return line downstream of the last injector. Fuel not used by the injectors is then returned to the reservoir via the return line.
Vehicle performance problems are a major concern in fuel rail designs. Vehicle barrier issues may negate the use of plastic fuel rails as well as plastic mounting brackets. Moreover, press-fitting an isolator onto a metal fuel rail requires more tooling and increases the number of maintenance issues to be addressed. Increased parts increases the probability of loose parts falling into the manifold and eventually into the engine block, potentially damaging the engine.
The need exists for a fuel rail design that does not suffer from the heat transfer problems inherent in the conventional designs and that does not increase the manufacturing, tooling and maintenance problems inherent in the conventional designs.
The present invention provides a simple method to incorporate an isolator to a metal fabricated fuel rail design with a minimal snap-on fit attachment load.
With the present invention, the number of loose parts during the fuel rail to intake manifold assembly process is reduced. Moreover, if vehicle barrier issues are of a concern, which may negate the use of a plastic fuel rail and a heat sink prone metal fabricated fuel rail is required, vehicle performance problems resulting from hot fuel handling may be addressed by incorporating the plastic isolators.
Alternatives to the use of the plastic isolators would be the use of a plastic fuel rail design or incorporating plastic mounting brackets to a metal fuel rail. However, vehicle barrier requirements and fuel rail packaging requirements on the intake manifold, may dictate a metal fuel rail design.
The structural arrangement of the present invention provides a fuel rail design that is more cost effective, that will meet stringent packaging and performance requirements, and that may be more conducive to efficient manufacturing initiatives. Barrier concerns can be addressed with use of metal fabricated fuel rails where protection of the fuel system is reduced. Packaging issues can be addressed where the intake manifold requires an unconventional fuel rail design, which may dictate a metal fuel rail process that does not permit a cost effective process such as plastic to be used, yet hot fuel handling may be a concern. Press fitting an isolator onto a metal fuel rail design requires more tooling and maintenance issues to be addressed. A manual, light force snap-fit installed isolator, as proposed by this invention, can make the overall manufacturing process more efficient and effective by improving handling at the assembly plant.
The plastic snap-on rail mounting isolator of this invention reduces the heat transfer from a metallic intake manifold to a metal fabricated rail. This heat transferral would potentially cause hot fuel handling vehicle driveability problems as well as heat the excess unused fuel from the fuel rail being returned back to the fuel tank. In turn, this can cause vehicle emission problems. The snap-on feature prevents loose parts from falling into the manifold and eventually into the engine block, potentially damaging the engine.
The provision of a simple snap-on plastic isolator with minimal assembly force effectively reduces the heat transfer of the engine to the fuel in the fuel rail assembly, hence reducing vehicle hot fuel handling and emission problems. This invention also affords greater design flexibility in offering customers more cost effective rail designs for their packaging constraints.